Single Phase Pulsating MMF starting method for Brushless WRSM

Qasim Ali,T. A. Lipo,Byung-il Kwon(권병일) 대한전기학회 2016 대한전기학회 학술대회 논문집 Vol.2016 No.10

Analysis for the Sub-Harmonically Excited, Brushless Wound Rotor Synchronous Machine

Qasim Ali,Byung-il Kwon(권병일) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.7

Polymeric Insulant Characterization via Partial Discharge Measurement

Qasim Khan,Furkan Ahmad,Asfar A. Khan 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.6

The selection of insulant for any power system required its characterization in addition to its testing; the effi cient and longevalspan of the insulant is vital even under extreme conditions. This paper characterizes the Polymer-based solid insulant viaPartial Discharge (PD) measurement using artifi cially created stress condition with the CIGRE-II based electrode systemover the polymer-based insulation sheets having simulated cavities of diff erent confi guration. Assessment of insulation usingPD features provides pre-breakdown situation and provide capability to comprehend the mechanism of insulant’s debilitation. The digital PD system is modern diagnosis toolkit (MPD 540) based on IEC 60270 with the competency of fi lteringinternal PD signals from external Interference and Discharges implement for collecting data. The evaluated PD voltages forartifi cially created voids vary in number and size in each polymer based dielectric sample to realize PD model. The controlledsized cavities signifi cantly infl uenced the PD inception and extinction voltage with variable size and a diff erent number ofcavities extant in dielectric samples. The possibility of PD process continuum or extinction after each discharge event ininsulation predicted using Weibull probability distribution for each distinct size cavity. The cylindrical cavity’s diameteralong the direction of the electric fi eld signifi cantly deteriorates the reliable operation of insulation as compared to its depth.

Experimental and analytical investigations of CFFT columns with and without FRP bars under concentric compression

Qasim S. Khan,M. Neaz Sheikh,Muhammad N.S. Hadi 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.6

This research study investigates experimentally and analytically the axial compressive behaviour of Concrete Filled Fiber Reinforced Polymer Tube (CFFT) columns with and without Fiber Reinforced Polymer (FRP) bars. The experimental program comprises five circular columns of 204-206 mm outer diameter and 800-812 mm height. All columns were tested under concentric axial compressive loads. It was found that CFFT columns with and without FRP bars achieved higher peak axial compressive loads and corresponding axial deformations than conventional steel reinforced concrete (RC) column. The contribution of FRP bars was about 12.1% of the axial compressive loads carried by CFFT columns reinforced with FRP bars. Axial load-axial deformation (P ‒ δ) curves of CFFT columns were analytically constructed, which mapped well with the experimental P ‒ δ curves. Also, an equation was proposed to predict the axial compressive load capacity of CFFT columns with and without FRP bars, which adequately considers the contributions of the circumferential confinement provided by FRP tubes and lower ultimate strength of FRP bars in compression than in tension.

PM Assisted, Brushless Wound Rotor Synchronous Machine

Qasim Ali,Shahid Atiq,Thomas A. Lipo,Byung-il Kwon 한국자기학회 2016 Journal of Magnetics Vol.21 No.3

This paper presents a new permanent magnet (PM) assisted topology for a recently introduced brushless wound rotor synchronous machine (BL-WRSM). The BL-WRSM had a dual-inverter configuration for generating a composite magneto motive force (MMF) with a fundamental component and a subharmonic component. The subharmonic component of the MMF is used for brushless excitation of the rotor. In this paper, additional PMs were introduced on the rotor of the BL-WRSM, making it a hybrid BL-WRSM. We also discussed the flux weakening operation for the hybrid BL-WRSM. The hybrid BL-WRSM offered advantages for starting the machine and provided better performance under full-load conditions. The finite element method (FEM) was used to analyze the performance of the hybrid BL-WRSM, and we compared its performance with BL-WRSM. Finally, prototypes were built with and without the PM-assistance, and experiments were conducted to demonstrate their performance.

Axial compressive behaviour of circular CFFT: Experimental database and design-oriented model

Qasim S. Khan,M. Neaz Sheikh,Muhammad N.S. Hadi 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.4

Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.

Nanotechnology for diagnosis and treatment of infectious diseases.

Qasim, Muhammad,Lim, Dong-Jin,Park, Hansoo,Na, Dokyun American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.10

<P>The emergence of co-infections and the evolution of drug-resistant pathogens limit the utility of current therapies against infections, and developing countries in particular are facing a great challenge in combating infectious disease. Moreover, any failure to control the spread of infectious diseases would also represent a threat to developed countries. Recent developments in nanotechnology allow us to address this issue at two levels: diagnostics and treatment. Prevention of the spread of infectious pathogens requires rapid and accurate identification of the infectious agents for proper treatment. Recently developed fluorescent nanoparticles are so sensitive that even a single nanoparticle is capable of emitting a strong enough signal to be captured, thus enabling early identification of infections. Proper and effective treatment not only saves the patient, but also prevents the spread of the pathogens. Specific nanoparticle vehicles developed to encapsulate therapeutic agents and deliver them to a target site represent a promising strategy to boost immune responses for vaccination and boost the efficacy of drugs for treatment. Here, we describe a variety of nanotechnologies for use in applications such as immune response modulation, drug delivery, diagnostics, and treatment, which are especially needed in developing countries.</P>

A Biomechanical Comparison of Intralaminar C7 Screw Constructs with and without Offset Connector Used for C6-7 Cervical Spine Immobilization : A Finite Element Study

Qasim, Muhammad,Hong, Jae Taek,Natarajan, Raghu N.,An, Howard S. The Korean Neurosurgical Society 2013 Journal of Korean neurosurgical society Vol.53 No.6

Objective : The offset connector can allow medial and lateral variability and facilitate intralaminar screw incorporation into the construct. The aim of this study was to compare the biomechanical characteristics of C7 intralaminar screw constructs with and without offset connector using a three dimensional finite element model of a C6-7 cervical spine segment. Methods : Finite element models representing C7 intralaminar screw constructs with and without the offset connector were developed. Range of motion (ROM) and maximum von Mises stresses in the vertebra for the two techniques were compared under pure moments in flexion, extension, lateral bending and axial rotation. Results : ROM for intralaminar screw construct with offset connector was less than the construct without the offset connector in the three principal directions. The maximum von Misses stress was observed in the C7 vertebra around the pedicle in both constructs. Maximum von Mises stress in the construct without offset connector was found to be 12-30% higher than the corresponding stresses in the construct with offset connector in the three principal directions. Conclusion : This study demonstrated that the intralaminar screw fixation with offset connector is better than the construct without offset connector in terms of biomechanical stability. Construct with the offset connector reduces the ROM of C6-7 segment more significantly compared to the construct without the offset connector and causes lower stresses around the C7 pedicle-vertebral body complex.

Beam Search Algorithm for Large Antenna Arrays Reducing Beam Search Time

Qasim Sultan,Yong Soo Cho 한국통신학회 2020 한국통신학회 학술대회논문집 Vol.2020 No.8

Dissolved oxygen and nitrate effects on the reduction and removal of divalent mercury by pumice supported nanoscale zero-valent iron

Qasim, Ghulam Hussain,Lee, Sangwook,Lee, Giehyeon,Lee, Woojin,Hong, Yongseok,Han, Seunghee The Royal Society of Chemistry 2018 Environmental science Vol.4 No.10

<P>A series of batch experiments were conducted to identify the effects of dissolved oxygen (DO) and nitrate on the removal and reduction of Hg(ii) by a pumice supported nanoscale zero-valent iron (p-nZVI) composite. After the adsorption and consecutive reduction of Hg(ii) in an anoxic solution, zero-valent iron, and ferrous and ferric irons were found on the surface of the p-nZVI with a chain-like structure; while in the oxic solution, a thick ferric shell was found on the surface of the p-nZVI with collapsed chain structures. In Hg(ii) sorption isotherm tests, with 25, 250, 1000, and 2500 nM of Hg(ii), the Hg(ii) sorption capacity of the p-nZVI was 6.1 mg g<SUP>−1</SUP> in the oxic aqueous solution and 1.5 mg g<SUP>−1</SUP> in the anoxic aqueous solution. While the adsorption of Hg(ii) was more favorable in the presence of DO, the headspace Hg(0), as well as dissolved Fe(ii), was largely increased in the absence of DO. The removal of Hg(ii) in oxic and anoxic suspensions was not affected by nitrate levels ranging from 0.08 to 8 mM. In contrast, Hg(0) concentration in headspace increased with an increase of nitrate, which was related to the enhanced dissolved Fe(ii) production. The experimental results of this study suggest that the absence of DO and the presence of nitrate in groundwater could significantly increase Hg(0) in groundwater and adjacent atmosphere during the usual remediation process using relevant nZVI techniques. The effective capture and treatment methods of Hg(0) should be developed for better application of p-nZVI-based technologies.</P>